Integral mask for color film



Sept. 21, 1948. w. T. HANSON, JR 2,449,966

INTEGRAL MASK FOR COLOR FILM Filed May 3, 1944 FIG. I.

CYAN C DYE YELLOW AGENTA Q DYE DYE [1.] D

.l 2 l- O. O

l I 400 500 600 700 FIG WAVE LENGTH B G R 40 RED ABSORPTION 6 M -GREENABSORPTION z P VBLUE ABSORPTION 4m 1.06. E LOG. E LOG .E

8 LBLUE &GREEN ABSORPTION PRINTED u RFD ABSORPTION INVENTOR BY mfw (3 MMA TTORNE YS WESLEY T. HANSONQJR.

' Patented 21, 1948 INTEGRAL MASK FOR COLOR FILM Wesley '1. Hanson, In,Knoxville, Tenn., assignor to'Ealtman Kodak Company, Rochester, N. Y., acorporation of New Jersey Application May 3, 1944, Serial No. 533,910 7Claims. (Oi. 95-2) This invention relates to photography andparticularly to a method for securing color correction in colortransparencies used for printing.

It is known that dyes used in subtractive multicolor photographicpictures do not transmit all of the light which theoreticalconsiderations demand. The cyan dye which should absorb red light andtransmit green and blue light usually absorbs a small amount of greenand blue light as well as a major proportion of red light. The magentadye which should absorb green light and transmit blue and red lightusually absorbs a considerable amount of blue light and a small amountof red light. The yellow dye which should absorb blue light and transmitgreen and red light is usually satisfactory although some-- times itabsorbs a small amount of green light. The result of printing amulti-color picture formed of such dyes is to introduce unequal parts ofall three records in each image which is made, regardless of the colorof light used in printing or the sensitivity of theprinting materialemployed. Correction of the colors on printing is therefore desirable,and this is usually done by masking, as described in prior patents, suchas Evans '0. S. Patent 2,203,653, granted June 4, 1940, and my priorPatent 2,294,981, granted September 8, 1942.

Since separate masks are diiiicult to register with the color picture,it is desirable that the mask be integral with the colored images. TheEvans U. 8. Patent 2,203,653, referred to above describes a method formaking an integral mask in a multi-layer reversal material, but the maskis black or gray in color and does not secure the advantages of coloredmasks such as described in Evans U. 8. application Serial No. 413,442,filed October 3, 1941, now U. S. Patent 2,376,132, granted May 15, 1945.

One type of color process in which it would be desirable to introducecolor correction is that in which a, color coupler is incorporated inthe sensitive emulsion layer prior to exposure. Processes of this typeare described, in Mannes and Godowslay Patent 2,304,940, grantedDecember 15, 1942, and Jelley and Vittum U. 8. Patent 2,322,027,

granted June 15, 1943. These processes are particularly useful asnegative-positive processes, a

in the negative perior making corrected my invention by incorporating inthe sensitive the dye may be emulsion layer a colored materialespecially a color coupler which absorbs the undesired absorption of adye reduced in image form in the layer. In case the colored material isa coupler, produced by coupling from the coupler itself therebydestroying the coupler in the portions of the layer in which an image isformed and leaving the coupler unailected in the remaining portions ofthe layer.

In the accompanying drawing,

Figure 1 is a, graph illustrating the spectral absorption ofrepresentative dyes used in subtractive color processes.

Figure 2 is a graphic representation of the relative absorptions ofrepresentative subtractive dyes obtained by plotting the exposureexpressed logarithmically against the optical density in various regionsof the spectrum.

Figure 3 is a representation, partly sectional and partly graphical, ofa photographic layer employing the correction method of my invention andshowing the correction obtained on printing.

In describing my invention, it will be necessary first to refer to thespectral absorption properties of typical dyes used in subtractive colorprocesess as illustrated in Figures 1 and 2 of the drawing.

Figure 1 shows the absorption curves of typical subtractive dyes,yellow, magenta and cyan. If the optical density of each or these dyesatvarious wave lengths is determined, the graphs shownin Figure i may beobtained. The yellow dye absorption is principally in the blue regionbetween 400 and 500 millimicrons, although there is some absorption inthe green region between 500 and 600 millimicrons. The magenta dyeabsorbs principally in the green region, although there is aconsiderable absorption in the blue region and a smaller absorption inthe red region between 600 and 700 millimicrons. The cyan dye absorbsprincipally in the red region, although there is a considerableabsorption in both the blue and the green spectral regions. Thesecharacteristics are fairly common to dyes generally used. although theabsorptions are not identical with those shown in Figure 1. producingsuch dyes are described in numerous prior patents such as Marines et al.U. S. Patents 2,039,730, granted May 5, 1936, 2,108,602, grantedFebruary 5, 1938, and 2,115,394, granted April 26, 1938. In Figure 1 itis assumed that the relative concentrations of the dyes are adjusted sothat when layers containing the three dyes are superposed, a neutralgray image is produced.

The absorption of the dyes of Figure l in the various regions of thespectrum are illustrated in the graphs of Figure 2. The separate graphsindicate the absorption gamma of each dye in one of the three regions ofthe visible spectrum. The horizontal rows 01 parts Y for exampleillustrate the absorptions of the yellow dye in the blue, green and redregions of the spectrum. The principal or major absorption of the dye isindicated by a solid line, and the minor absorptions by dotted lines.The graph YB therefore illustrates. the absorption of the yellow dye inthe blue region, the graph MG illustrates the absorption of the magentadye in the green region and the graph CR illustrates the absorption ofthe cyan dye in the red region.

The curves of Figure 2 are H and D curves of the dye images in variousspectral regions and are said to represent absorption gamma, that is,the H and D curve of the dye image as read by light of any spectralregion. For example, the curve YB represents the absorption gamma of theyellow dye whenread by blue light.

It is apparent from the graphs of Figure 2 that in a duplicationprocess, blue light will be absorbed not only by the yellow dye but alsoto some extent by the magenta and cyan dyes. Similarly, green light willbe absorbed not only by the magenta dye but also to a certain extent bythe yellow and cyan dyes. Red light will be absorbed not only by cyandye but also to a small extent by the magenta dye. This lowers thesaturation of the dyes in the print and tends to make the colors dirtyor degraded. The known masking methods seek to overcome thisobjectionable feature of the dyes by inserting a density which cancelsout the undesired absorptions of one or more of the dyes.

It is apparent from a consideration of Figure 2 of'the drawing that ifthe absorptions CB and- CG of the cyan dye could be canceled by placingover the cyan image an image of opposite sign and absorptions equal tothe absorptions CB and CG, the efiect would be to introduce a neutraldensity in these regions without affecting the absorptionCR. The mannerin which this is accomplished according to. my invention is illustratedin Figure 3 of the drawing.

Figure 3 is in the form of a cross-section of an emulsion layercontaining dye images. according to my invention, the dye images beingillustrated Color couplersby means 01' their absorption gamma for thepurpose oi illustration. The sections la and 4b of 6, I, and 8.

Figure 3 are portions of the same layer but are separated for purposesoi! clarity in illustration. As shown in 4a, the emulsion layer containsa cyan dye image, the red absorption gamma 0! which is illustrated bycurve 5. The cyan dye image has minor absorptions of green and bluelight as illustrated by the-absorption gamma I and 1 respectively. Thesecurves correspond to the curves CR, CG, and CB, respectively, but aresuperposed in Figure 3.

in the same layer as the cyan dye in at, there is a coloring materialhaving an absorption gamma illustrated at 8 in 4b which is equal andopposite in gamma to the gamma 0! 6 or I or the average of these gammas.It is opposite in sign, that is it is a positive image when 6 and Irepresent a negative image. Since the coloring material represented at 8has blue and green light absorption, it adds to the blue and greenabsorption of the cyan dye as represented at 6 and 'l and thereforeproduces the same result as removing the absorptions represented at 6and I, by converting them into non-image-forming, overall blue-greenabsorbers.

When the negative image in 4a is printed onto the film 9 the effect ofthe over-all blue-green absorption is illustrated as a straight line l0and the absorption gamma of the cyan image is illustrated at II. It willbe seen that the contrast oi the cyan image to blue and green light isreduced to zero because of the combined effect of images More blue andgreen exposure is therefore required in printing those records, and thecontrast of the yellow and magenta images must be. raised, either in theoriginal or in the print.

' sky U. 5. Patent 2,304,940 or the Jelley and Vittum U. 8. Patent2,322,027, referred to above. The coupler need not be incorporated in a.waterpermeable, water-insoluble solvent as described in those patentsbut may be incorporated in insoluble or non-difiusing form in theemulsion. The

coupler is colored so that it absorbs light prior to coupling but uponcoupling is converted to a form which absorbs the color desired for thefinal dye image. The color of the original coupler is chosen so that itabsorbs light of the same color as the undesired absorption of the dyeformed from it. In this way, the colored coupler can correct for theimproper absorption of the coupled dyes and thus effect completemasking. Depending upon the correction desired, the cyan coupler shouldbe red, orange or yellow, the magenta coupler yellow or green and theyellow coupler magenta or blue. The reason for choosing-these colors isapparent from a consideration of Figure 2 of the drawing.

The red, orange, or yellow coupler used for the cyan dye absorbs blue orblue and green lightwhich the cyan dye also absorbs but which it shouldtransmit. The yellow coupler used for the magenta dye absorbs 'bluelight which the magenta dye absorbs but which it should transmit. Themagenta coupler used for the yellow dye absorbs green light which theyellow dye absorbs to a small extent but which it shouldtransmit. Thefollowing couplers describedin application Serial Nos. 533,930, 533,931and 533,932, flied cases a May 8,184, by Glass, vittum and Weissbergerare suitable for use according to my invention:

.velopment of the re Colorol Coupler 832: Coupled CcBrN\ lin-N=N-c.nr-on 4 Ycllowm. Magenta.

CoKr-CO-H-N=NCQKI man .Do.

, coon do Do. CN c0-cHN=N o no N=NCsHr-OCH1(4) Red Blue.

I- Cu u(fl) CsEr-N\ l conN=N- 0om Yellow-... Magenta. a.

N COOH Red Cyan.

1. CO-NH CQHI mm-co-ln-rvmLQmm Orange-red Yellow.

Analternative method of introducing the correcting image into theemulsion layer is to use, instead of a colored coupler, a dye which canbe bleached in the presenceof silver. If such dye is introduced into theemulsion layer along with the coupler, the choice of coupler is notlimited to the color which it has before coupling, and there is also a.wider choice of bleachable dyes. If a red or orange dye is incorporatedin the red-v sensitive layer for example, a positive image will beobtained from this dye if, after negative color development, the film isimmersed in a bleached bath which destroys the masking dye in thepresence of silver but does not affect the dye formed by coloring. Inthe presence of the negative silver image, the dye will be bleached andwill leave a positive image.

It is apparent that the masking image used according to my invention isoi sign opposite to that o! the image dye. I! the image dye is anegative, the masking dye will be a positive and vice versa. Where Irefer in the claims to a negative color image, it is to be understoodthat I mean that it is negative with regardto the masking image orofopposite sign. It may be. any image which-is printed either from anegative or a positive.

While I prefer to use my method in a negativepositive process, it isalso applicable to a reversal process. Where the masking image is acolored coupler, a. .black-and-white negative developer must be used andthe negative silver thus formed may be leit in the film until after thecolor desilver image of a reversal process must be removed beforereversal development and bleaching of the dye.

The following example illustrates one method of producing a correctedimage according to my invention.

Example sensitive layer containing a coupler yielding a magenta dyeimage, (4) yellow filter layer, and (5) blue-sensitive layer containinga coupler yielding a yellow dye image. This example will showa materialin-which a colored coupler is used in the green-sensitive layer toprovide a corrected magenta dye image. The details of the preparation ofthe several layers are given in the following paragraphs.

Red-sensitioe layen-This is prepared accordm to the description '-inJelley and Vlttum U. s.

Patent 2,322,027; page-i, Example 2. The coupler employed is5(N-benzyl-N-naphthalene sulfonamino) 1-naphthol, dispersed in ethyl N,N-di-m butyl carbamate, and the emulsion to which it is added isred-sensitized by known means.

Green-sensitive lawn-The coupler used in.

this ,layer is 1-phenyl-3-n-pentadecyl-4-p-methoxyphenylazo-S-pyrazolone. This coupler is yellow and reacts with theoxidized developer to produce a magenta dye. Seven and a halt gramssilver halide: It the masking image is a bleachable dye. "the negativeof the coupler are dissolved in 22.5 g. of tri-ocresylphosphate bygentle warming and this solution is emulsified with 40 cc. oi. 2%gelatin solution containing 1.5 g. of tri-isopropylnaphthalone sulfonateby passing the whole mixture through a colloid mill several times. Theresulting emulsion is added to 1,000 cc. of a melted silver halideemulsion which has beensensitized to green. and the mixture coated overthe redsensitive layer described above.

Yellow-filter lawn-This layer contains yellow colloidal silver a knownfrom the prior art.

Blue sensitive layer.'1his is prepared according to the description inJelley-& Vittum U. S.

2,322,027, page 4, Example 6. The coupler employed is N (4benzoylacetaminobenzonesulfonyD-N-benzyl-m-toluidine, dispersed in ethylbenzylmalonate.

The composite coating prepared in the above manner is developed in thefollowing solution, after exposing in the normal manner:

2-amino-5-diethylaminotoluene hydrochloride grams 2 Sodium sultlte(anhydrous) do 2 Sodium carbonate, monohydrate do 20 Potassium bromidedo 2 Water c 1,000

The time of development will depend on the nature of the particularsilver halide emulsions employed. Development is followed by an acidhardening fixing bath and a silver removal bath according to well knownpractices.

The processed material thus obtained will contain a normal negativeimage in cyan dye in the red-sensitive layer, and a normal negativeimage in yellow dye in the blue-sensitive layer. The green-sensitivelayer will contain a negative image in magenta dye, and the residualcoupler will make a reversed image of yellow coupler.

This negative image can be printed onto a normal multi-layer printingmaterial for the production of three-color photographs.

Instead of introducing the colored coupler to the sensitive emulsionlayer, the sensitive layer may be treated with a diazonium salt solutionprior to color development in order to produce the colored coupler inthe layer. A variety of diazonium solutions may be used for thispurpose, and the time during the production of the film to which thereaction with the diazonium solution is carried out may also bemodified. Either of these conditions may be changed to give a number ofdiii'erent results. For example, the diazo coupling can be carried outwhen only part of the layers have been coated, that is, when only thered-sensitive layer or only the redand green-sensitive layers have beencoated. Diazo coupling 01' the complete multi-layer material can also becarried out at difierent times, such as before or after exposure. In thecase of multilayer coatings, the character of the couplers and sults andwill vary according to the desired ab-'.

sorption to be gained and to the ease with which it may be handled. Ingeneral, however, the procedure is rapid and complete and may bemodified in a number of ways as shown above.

As a specific example of the preparation of a colored coupler in thisway, agreen-sensitive emulsion, such as that described in the specificexample above but using as the coupler -(pbutylphenoxy) propionylaminoJ-S-pyrazolone is treated as the'exposure but before colordevelopment with a diazonium solution prepared in .the following manner.

1.2 grams p-anisidine (0.01 mole) dissolved in cc. of water and 5 cc. ofconcentrated hydrochloric acid is diazotized with 1.5 grams sodiumnitrite in 15 cc. water at 5-10 C. The excess of nitrous acid isdestroyed with sulfamic acid, and cc. 01' a 10% sodium acetate solutionis then added. The resulting solution is then used for the diazocoupling at a temperature between and F., the film being left in itanywhere from a few seconds to about ten minutes at which time couplingis complete.

The masking method which I propose to use has all the advantages ofknown masking methods with the additional advantages of the colored maskdescribed in Evans U. S. application Serial No. 413,442, now U. S.Patent 2,376,132, and the advantages of an integral mask. Lack 01'registry between the mask and the picture image is no problem with myinvention.

It is thereby understood that the modifications and examples discolsedherein are by way of example only and that I consider as included in myinvention all modifications and equivalents coming within the scope ofthe appended claims.

I claim:

1. The method of forming a color corrected image in a photographicelement having superposed silver halide emulsion layers sensitive todifierent regions of the visible spectrum, at least one of said layerscontaining a colored color coupler for color-forming development havinga chromophore-containing group in the position in the coupler which isreactive with the oxidation product of a primary aromatic aminodeveloping agent, said chromophore-containing group being split off withsimultaneous conversion of the residual group 01' the colored coupler tocoupled dye by color development to form a dye image which absorbs amajor proportion 01' light in the spectral region oi. one of the primarycolors and a minor proportion 01 light in at least one other region ofthe visible spectrum, said colored coupler absorbing light in at leastone of said minor absorption regions but absorbing no substantial amountof light in said major absorption region, which comprises exposing saidlayers to light and developing at least said layer containing saidcolored coupler by color development with a primary aromatic aminodeveloping agent, said color development resulting in splitting off thechromophore-containing group of said colored coupler where said dyeimage is formed by coupling, leaving in the undeveloped regions of saidone layer colored coupler absorbing light in said minor absorptionregion or said dye image.

2. The method oi. forming a color corrected image in a photographicelement having superposed silver halide emulsion layers sensitive todifferent regions of the visible spectrum, at least one of said layerscontaining a dispersion in a water-permeable, water-insoluble solvent,of a colored color coupler for color-forming development having achromophore-containing group in the position in the coupler which isreactive with the oxidation product of a primary aromatic aminodeveloping agent, said chromophore-consion of the residual group taininggroup being split of! with simultaneous conversion or the residual groupof the colored coupler to coupled dye by color development to form a dyeimage which absorbs a major proportion of light in the spectral regionof one of the primary colors and a minor proportion of light in at leastone other region of the visible spectrum, said colored coupler absorbinglight in at least one or said minor absorption regions but absorbing nosubstantial amount of light in said major absorption region, whichcomprises exposing said layers to light and developing at least saidlayer containing said colored coupler by color development with aprimary aromatic amino developing agent, said color developmentresulting in splitting ofl the chromophore-containing group of saidcolored coupler where said dye image is formed by coupling, leaving inthe undeveloped regions of said one layer colored coupler absorbinglight in said minor absorption regions of said dye image.

3. The method of forming a colored corrected image in a photographicelement having superposed silver halide emulsion layers sensitive todifferent regions of the visible spectrum, at least one of said layerscontaining a colored color coupler tor color-forming development havingan azo group in the position in the coupler which is reactive with theoxidation product of a primary aromatic amino developing agent, said azogroup being'split ofl with simultaneous conversion of the residual groupof the colored coupler to coupled dye by color development to form a dyeimage which absorbs a major proportion of light in the spectral regionof one of the primary colors and a minor proportion of light in at leastone other region of the visible spectrum, said colored color couplerabsorbing light in at least one of said minor absorption regions butabsorbing no substantial amount of light in said major absorptionregion, which comprises exposing said layers to light and developing atleast said layer containing said colored coupler by color developmentwith a primary aromatic amino developing agent, said color developmentresulting in splitting of! the azo group of said colored coupler wheresaid dye image is formed by coupling, leaving in the undeveloped regionsof said one layer colored coupler absorbing light in said minorabsorption region of said dye image.

4. The method of forming a color corrected image in a photographicelement having superposed silver halide emulsion layers sensitive todiflerent regions of the visible spectrum, at least one of said layerscontaining a colored color couimage in a pler ior color-formingdevelopment having an v azo group in the position in the coupler whichis reactive with the oxidation product of a primary aromatic aminodeveloping agent, said azo group being split off with simultaneousconverto coupled dye by color development to form a cyan dye image whichabsorbs a major proportion of red light and a minor proportion ofvisible light of shorter wave length than red, said couof the coloredcoupler pler absorbing light insaid region of shorter 7 wave length butabsorbing no substantial amount of red light, which comprises exposingsaid layers to light and developing at least said layer containing saidcolored coupler by color development with a primary ing agent, saidcolor development resulting in splitting off the azo group or saidcolored coupler where said cyan dye image is formed by coupling, leavingin the undeveloped regions of said aromatic amino developone layercolored coupler absorbing light in said minor absorption region of saidcyan dye image.

5. The method 01 forming a color corrected image in a photographicelement having superposed silver halide emulsion layers sensitive todiflerent regions of the visible spectrum, at least one of said layerscontaining a colored color coupler for color-forming development havingan azo group in the position in the coupler which is reactive with theoxidation product of a primary aromatic amino developing agent, said azogroup being split oil with simultaneous conversion of the residual groupof the colored coupler to coupled dye by color development to form acyan dye image which absorbs a major proportion of red light and a minorproportion of blue and green light, said coupler absorbing blue andgreen light but absorbing no substantial amount of red light, whichcomprises exposing said layers to light and developing at least saidlayer containing said colored with a primary aromatic amino developingagent, said color development resulting in splitting oi! the azo groupand destruction oi the color of said colored coupler where said cyanimage is formed, leaving blue-green absorbing coupler in the undevelopedregions of said one layer.

6. The method of forming a color corrected image in a photographicelement having superposed silver halide emulsion layers sensitive todiflerent regions of the visible spectrum, at least one of said layerscontaining a red colored coupler capable of forming a cyan dye bycoloriorming development and having an azo group in the position in thecoupler which is reactive with the oxidation product of a primaryaromatic amino developing agent to form said cyan dye, said azo groupbeing split oil with simultaneous conversion of the residual group ofthe coupler to a cyan dye by color development, which comprises exposingsaid layers to light and developing at least said layer containing'saidred colored coupler with a primary aromatic amino developing agent toform dye images representing color separations of a subject. one of saidcolor separations being formed by color development of said red coloredcoupler to a cyan dye, said color development resulting in splitting offthe azo group and destruction of the color of said coupler where saidcyan dye image is formed, leaving red colored coupler inthe undevelopedregions of said one layer.

7. The method of forming a color corrected photographic element havingsuperposed silver halide emulsion layers sensitive to diflerent regionsof the visible spectrum, at least one of said layers containing a yellowcolored coupler capable of forming a magenta dye by color-formingdevelopment and having an azo group in the position in the coupler whichis reactive with the oxidation product of a primary aromatic aminodeveloping agent to form said magenta dye, said azo group being splitof! with simultaneous conversion of the residual group of the coupler toa magenta dye by color development, which comprises exposing said layersto light and developing at least said layer containing said yellowcolored coupler with a primary aromatic amino developing agent to formdye images representing color separations of a subject, one of saidcolor separations being formed by color development of said yellowcolored coupler to a resulting in splitting oil the azo group anddecoupler by color development magenta dye, said color development 7magenta dye image is formed, leaving yellow colored coupler in theundeveloped regions of iile of this patent: 1 1

UNITED STATES PATENTS Name Date Michaelis Mar. 19. 1940 Michaelis May13, 1941 Schultze Jan. 5, 1943 FOREIGN PATENTS Country Date GreatBritain Apr. 11, 1939

